Peri-implant tissues morphometry at SLActive surfaces. An experimental study in the dog.

OBJECTIVE: The objective was to study tissue components around implants with highly hydrophilic surfaces during early healing. MATERIALS AND METHODS: In 12 Labrador dogs, the second and third mandibular premolars were extracted bilaterally. After 3 months of healing, full-thickness flaps were elevated in the edentulous region of one side of the mandible. An implant was installed, and the flaps were sutured to allow a non-submerged healing. The timing of the implant installations in the other side of the mandible until sacrifices were performed in such a way to collect biopsies representing healing after 4, 7, 15, and 60 days. An n = 6 was achieved for each healing period. Paraffin sections were obtained for morphometric analyses. RESULTS: Provisional matrix with a percentage of 32.9 ± 16.7% was found already after 4 days. This percentage became 37.3 ± 8.5%, 24.3 ± 9.1%, and 1.6 ± 1.7 after 7, 15, and 60 days, respectively. New bone was found after 7 days of healing, at a percentage of 26.2 ± 3.2%. This proportion increased to 36.0 ± 9.6% and 50.4 ± 8.3% after 15 and 60 days, respectively. Marrow spaces free from a blood clot, inflammatory cells, and provisional matrix represented a low proportion of the tissues after 4 days (1.6 ± 2.4%). This proportion increased over time to 9.2 ± 6.4%, 20.3 ± 12.9%, and 37.9 ± 9.6%, respectively. The percentage of old bone was noted in a similar percentage (~8%) up to 15 days. The percentage decreased to ~5% at 60-day of observation. CONCLUSION: The tissue changes observed during the healing were similar to those from historic controls studying healing in a chamber adjacent to implants. Hence, the characteristics of the implant surfaces may not be reflected in the tissue composition adjacent to the implant but rather affect the adhesion of tissue onto the implant surfaces.

Influence of bone marrow on osseointegration in long bones: an experimental study in sheep.

AIM: To evaluate the influence of yellow bone marrow on osseointegration of titanium oral implants using a long bone model. MATERIAL AND METHODS: The two tibiae of eight sheep were used as experimental sites. Two osteotomies for implant installation were prepared in each tibia. At the control sites, no further treatments were performed while, at the test sites, bone marrow was removed from the osteotomy site with a curette to an extent that exceeded the implant dimensions. As a result, the apical portion of the implants at the control sites was in contact with bone marrow while, at the test sites, it was in contact with the blood clot. After 2 months, the same procedures were performed in the contralateral side. After another month, the animal was sacrificed. Ground sections were obtained for histological analysis. RESULTS: After 1 month of healing, no differences between test and control sites were found in the apical extension of osseointegration and the percentage of new bone-to-implant contact. However, after 3 months of healing, a higher percentage of new bone-to-implant contact was found at the test compared to the control sites in the marrow compartment. The apical extension of osseointegration, however, was similar to that found at the 1-month healing period both for test and control sites. CONCLUSIONS: Osseointegration appeared to be favored by the presence of a blood clot when compared to the presence of yellow fatty bone marrow. Moreover, the contact with cortical bone appeared to be a prerequisite for the osseointegration process in the long bone model.